Entanglement dynamics in minimal Kitaev chains

TL;DR

This paper explores how entanglement evolves in minimal Kitaev chains, revealing controllable entangled states and the influence of Majorana quasiparticles, with implications for quantum information processing.

Contribution

It introduces a detailed analysis of entanglement dynamics in two- and three-site Kitaev chains, highlighting the role of Majorana quasiparticles and tuning parameters in generating highly entangled states.

Findings

Maximally entangled states can be robustly generated in two-site chains.

Majorana quasiparticles cause oscillations between entangled and separable states.

Three-site chains can produce GHZ or W-type entangled states depending on initial conditions.

Abstract

Minimal Kitaev chains host Majorana quasiparticles, which, although not topologically protected, exhibit spatial nonlocality and hence expected to be useful for quantum information tasks. In this work, we consider two- and three-site Kitaev chains and investigate the dynamics of bipartite and multipartite entanglement by means of concurrence and geometric measure of entanglement. In two-site Kitaev chains, we find that maximally entangled states can robustly emerge, with their stability and periodicity highly controllable by the interplay between the superconducting pair potential and the onsite energies. At the finely tuned sweet spot, where Majorana quasiparticles appear, the system exhibits oscillations between separable and entangled states, whereas detuning introduces tunable valleys in the entanglement dynamics. Extending to the three-site Kitaev chain, we uncover rich bipartite and multipartite entanglement by generalizing the concepts of concurrence and geometric measure of entanglement. At the sweet spot, the Majorana quasiparticles emerging at the edges suppress concurrence between the edges, while a finite detuning is able to restore it. Depending on the initial state, the three-site Kitaev chain can dynamically generate either a maximally entangled Greenberger-Horne-Zeilinger state or an imperfect W-type state exhibiting multipartite entanglement, although a (maximally entangled) pure W state cannot be realised due to parity constraints. Our results provide a resource for generating and characterising highly entangled states in minimal Kitaev chains, with potential relevance for quantum applications.